refactor(api): rename scan_frequency_minutes to scan_poll_interval_seconds

- Update API field from scan_frequency_minutes to scan_poll_interval_seconds
- Update database schema default value key
- Update Bruno API collection requests and documentation
- Update OpenAPI documentation examples and field descriptions

bruno/system/update-scan-settings.yml

@@ -4,22 +4,22 @@ info:
   seq: 2
 http:
   method: PUT
-  url: '{{base_url}}/api/libraries/scan-settings'
+  url: "{{base_url}}/api/libraries/scan-settings"
   auth: inherit
   body:
     type: json
     json:
-      scan_frequency_minutes: 30
+      scan_poll_interval_seconds: 30
       auto_scan_enabled: true
   headers:
-  - key: Content-Type
-    value: application/json
+    - key: Content-Type
+      value: application/json
 
 docs: |-
   ## Update System Scan Settings
-  
+
     Updates system-wide scan settings that apply to all libraries.
-  
+
     **Authentication**: Admin token required
     **Request**: Scan frequency (15-1440 minutes) and enabled status
     **Response**: Success message